The tanker crew gathered their courage and carefully navigated along a route designated by Iran, hugging the coastline and maneuvering their hulking vessel between island checkpoints through the Strait of Hormuz.

The 330-meter-long Agios Fanourios I, laden with Iraqi crude oil and bound for ⁠Vietnam, had been bottled up off the coast of Dubai since late April. But on May 10 it set off for the strait after a direct deal with Iran overseen by Iraq’s prime minister.

Iran’s orders to the tanker were part of a complex, multitiered mechanism that the country has deployed for clearing vessels through the Strait of Hormuz.